feat(global) several major updates:

- delete page `tag`, `archive`
- add page `friends`
- implement page `about` *partially*

frontend/app/page.tsx

@@ -3,10 +3,8 @@ import React from 'react';
 
 export default function Home() {
     return (
-        <main>
-            <div className={ `h-dvh` }>
-                <ConstructionPlaceHolder />
-            </div>
-        </main>
+        <div className={ `h-dvh` }>
+            <ConstructionPlaceHolder />
+        </div>
     );
 }